Sap suckers: A novel bird 'Guild' in wet sclerophyll forests of tropical North Queensland

[Extract] The sap of the Red Stringybark or Red Mahogany Eucalyptus resinifera is an important dietary component for the northern race of the Yellow-bellied Glider Petaurus australis reginae, locally named the Fluffy Glider (Quin 1996). In north-east Queensland, Yellow-bellied Gliders are classified as vulnerable, with a distribution limited to the wet sclerophyll forests at the western edge of the rainforest, between Daintree and Cardwell (Maxwell et al.1996). Harrington & Sanderson (1994) have shown that these wet sclerophyll forests have contracted by more than 50% in the past 50 years due to logging and invasion by rainforest. Yellow-bellied Gliders emerge at night to forage on sap, which is obtained by biting out small patches of bark from the trunk or main branches. Only E.resinifera is exploited in this way in north-east Queensland whereas a number of species of eucalypt are used in other parts of Australia (Russell 1995). Sap continues to exude during the day and birds regularly feed at the active sap-scars, an event that has been reported only by Russell (1981) in north-east Queensland. Goldingay (1996) briefly mentions diurnal use of the sap-feeding wounds but provides no details. This paper reports our observations of the species of bird using sap-scars; we discuss this behaviour and the factors influencing its occurrence.